Electronic devices are required to be smaller and thus a capacitor as an element of the electronic devices must be made smaller.
Capacity of a capacitor is calculated according to the following equation: EQU C=.epsilon.'.epsilon..sub.0 (S/d)
wherein .epsilon.' is specific permittivity of a dielectric material, .epsilon..sub.0 is specific permittivity of vacuum (0.0885 pF/cm), S is a surface area of the capacitor and d is a thickness of the capacitor. As is clear from the above equation, .epsilon.' and S must be made large and d must be made small in order to obtain the capacitor having smaller size and larger capacity.
Although the polymeric material is easily made in the form of a thin film having a large area, its specific permittivity is as small as 2 to 5. In order to produce a small capacitor having high performance, a dielectric polymeric material having large specific permittivity is required. The copolymer of VdF and TrFE is known as a highly dielectric polymeric material (cf. U.S. Pat. No. 4,173,033). The specific permittivity of the VdF/TrFE copolymer is about 15 (at a room temmperature and 1 KHz), which is 1.5 to 2.0 times larger than that of PVdF which has been known as a good polymeric dielectric material.
As a result of the extensive study on the dielectric properties of fluoropolymers, particularly VdF/TrFE copolymers, it has now been found that a VdF/TrFE/HFP terpolymer has excellent dielectric properties.